1. Field of the Invention
The present invention relates to an ink jet recording apparatus. More particularly, the invention relates to an ink jet recording apparatus that can perform recording without marking marginal portions at the edges of a recording medium. The invention also relates to an ink jet recording method therefor.
2. Related Background Art
Conventionally, for example, the ink jet recording apparatus, which records on a paper sheet, cloth, a plastic sheet, an OHP sheet, and other recording media by discharging ink with pressure exerted by bubbles created when film boiling is generated in ink by the application of heat generated by electrothermal transducing elements, is able to perform recording in high density at high speed. The ink jet recording apparatus is, therefore, utilized and merchandised as output means of information processing systems, such as a printer, among other systems.
Also, for the ink jet recording apparatus, it has been attempted to arrange the nozzles for discharging ink in a higher density, to make the discharging ink droplets finer, and to provide a higher quality image that may be comparable with a photograph by the application of technologies that enable ink of different densities to be used or the like. As a result, it becomes possible to market an ink jet recording apparatus even in such a field as image transmission for medical use in which the operation has been carried out by use of a silver salt photograph or the like.
Generally, an ink jet recording apparatus comprises a carriage having detachably mounted thereon a recording head and ink tank that serve as recording means; carrying means for carrying a recording medium; and control means for controlling those means. Then, the recording head that discharges ink from a plurality of discharge ports is arranged, on one hand, to serially scan in the direction (hereinafter referred to as the main scanning direction) orthogonal to the carrying direction (hereinafter referred to a the sub-scanning direction) of a recording medium, and, on the other hand, the recording medium is intermittently carried in the sub-scanning direction at a given pitch at the time of a non-recording operation.
FIG. 17 is a side view which schematically shows the structure of the principal part of the conventional ink jet recording apparatus 203 of the kind described above. FIG. 18 is a perspective view which schematically shows such ink jet recording apparatus.
The conventional ink jet recording apparatus 203 comprises a recording medium supply unit 221 that supplies a recording medium 216; a recording unit 222 that performs recording by use of an ink jet recording head cartridge 224 mounted on a carriage (not shown) on the recording medium 216 which has been fed; and an exhaust sheet unit 223 which receives the exhausted recording medium 216 after recording by the recording unit 222.
Hereunder, a brief description will be made of the operation of the conventional ink jet recording apparatus 203 to record on the recording medium 216.
A number of recording mediums 216, which are stacked and set on a pressure plate 217, are pressed by the pressure plate 217 to a separation roller 218, and separated one by one by separating means, such as separation nails (not shown) and the separation roller 218. After that, the recording medium thus separated is carried to first sub-scanning rollers 208 and 209 along guide plates 219 and 220. Then, the recording medium 216 is nipped by the first sub-scanning roller 208 and 209 and carried to the recording unit 222 where recording is effected with ink discharged from a recording head 212 of the ink jet recording head cartridge 224 formed of an ink tank 213 and the recording head 212, while the position of the recording medium is regulated by means of a platen plate 215. The ink tank 213 stores ink for its supply to the recording head 212. The recording head 212 is provided with a plurality of discharge ports arranged in the sub-scanning direction (indicated by an arrow K in FIG. 18) which is the carrying direction of the recording medium 216. Also, in recording, the carriage (not shown) that mounts the ink jet recording head cartridge 224 thereon performs the recording by reciprocating in the main scanning direction (indicated by an arrow J in FIG. 18), which is orthogonal to the sub-scanning direction, along the carriage guide (not shown) arranged substantially in parallel with the rotational shaft of the sub-scanning roller. After recording, the recording medium 216 is exhausted to a recording medium receptacle 214 while being nipped by the second sub-scanning rollers 210 and 211. Roller 211 of the second sub-scanning rollers is in the form of a spur in order to avoid the adhesion of wet ink, because this roller is in contact with the recording medium immediately after recording.
The carriage is moved above predischarging ports 202 before recording, and ink is predischarged so that the recording head 212 is readied for performance of good recording. Conventionally, the predischarging ports 202 are arranged outside the carrying path of the recording medium 216 as shown in FIG. 18 so that staining of the recording medium 216 by ink that adheres to the predischarge ports 202 is avoided.
Also, on the recording medium 216, there are a recording area 201a where recording is effected, and non-recording areas 201b which become marginal portions where no recording is effected as shown in FIG. 18. If recording is effected on the non-recording areas 201b, ink may adhere to the platen plate 215, and the recording medium 216 will be stained. The non-recording areas 201b are used in order to avoid this problem.
However, with the structure of the conventional example described above, there are problems encountered as described below when transmitted images are made for medical use, for example.
FIG. 19 is a view which shows one example of a transmitted image 204 for medical use where recording is effected on a transparent recording medium by use of the conventional ink jet recording apparatus. Also, FIG. 20 is a view which shows the state where transmitted images 204 and 204xe2x80x2 are arranged side by side on a light box 205 for observation.
On the circumference of the image areas 204a, an area, which is called a border 204b, is formed where areas other than images are covered with black color in high density. Further, on the circumference of the border 204b, transparent areas having no recording on them are formed as the non-recording areas 204c, 204d, 204e, and 204f. 
As shown in FIG. 20, the transmissive image 204 is in a state where it is inserted on the upper portion of the front face of the light box 205. Then, the image area 204a is observed by applying back light to the reverse side of the transmissive image 204 from the light box 205. Therefore, in a case of a silver salt photograph, all the portions other than medical images are treated as the borders. When this photograph is observed in the light box 205, unwanted light is blocked. This is because intensified light is emitted from the unwanted transparent portions, if any, and the intended observation is hindered on the portions that should be examined precisely.
Here, the transmissive image 204, which is recorded by use of the conventional ink jet recording apparatus, presents the transparent areas 204c, 204d, 204e, and 204f which are formed on the circumference of the border 204b without any recorded images. When a transmitted image 204 of this kind is mounted on the light box 205 for observation, the light that transmits through the non-recording areas 204d and 204e on both edges, respectively, in particular, hits the eyes of the observer to hinder the precise observation of the image area 204a. Also, as shown in FIG. 20, plural numbers of transmitted images 204 and 204xe2x80x2 are often observed at one time. In this case, when each of the image areas 204a and 204axe2x80x2 of the respective transmissive images 204 and 204xe2x80x2 is intently observed one after another, such gaze of the observer may shift across the transmissive image 204 and the transmissive image 204xe2x80x2. Then, the eyes of the observer, which have gazed upon the weaker luminous energy on the image area are dazzled by the intense light that transmits through the transparent marginal portions of the non-recording areas 204e and 204d, hence making it impossible, in some cases, to perceive the minute change of luminous energies on the image areas 204a and 204axe2x80x2 to be observed next.
As an apparatus that may be able to solve the problems discussed above, an ink jet printer is disclosed in the specification of Japanese Patent Application Laid-Open No. 8-169155, wherein on the lower side of the printing head of such printer, there is provided an ink collection container having a sufficient width which is larger than the width of a recording sheet to be carried across the range of the printing head reciprocation.
Nevertheless, the ink jet printer disclosed in the specification of the aforesaid laid-open application does not provide any guiding members that guide a recording sheet over the entire width of the recording sheet on the lower side of the printing head, and the recording sheet is carried in a state where it floats in the air. As a result, the behavior of the recording sheet is unstable. Further, the behavior of the recording sheet becomes more unstable when the ink droplets discharged from the printing head are absorbed into the recording sheet, hence presenting an unfavorable problem that the quality of recorded images is degraded.
It is an object of the present invention to provide an ink jet recording apparatus capable of recording up to the edges of a recording medium in high quality, and also, to provide an ink jet recording method therefor.
It is another object of the present invention to provide an ink jet recording apparatus which comprises carrying means for carrying a recording medium; a head installation unit for a recording head to record on the recording medium by discharging ink from discharge ports, which reciprocates in the width direction intersecting the carrying direction of the recording medium; supporting means for supporting the recording medium in a position facing the recording head; and opening portions for collecting ink discharged from the recording head at the edges of the recording medium in the width direction.
It is still another object of the present invention to provide an ink jet recording apparatus which comprises carrying means for carrying a recording medium in the carrying direction of the recording medium, a head installation unit for mounting the recording head to record on the recording medium, which discharges ink from a plurality of discharge ports arranged in a range exceeding the passage area of the recording medium in the width direction intersecting the carrying direction; supporting means for supporting the recording medium in a position facing the recording head; and opening portions for collecting ink discharged from the recording head at the edges of the recording medium in the width direction.